int prime(int n)
{
    if(n==1)
        return 0;
    if(n==2)return 1;
    if(n%2==0)return 0;
    int c=3;
    for(;c*c<=n;c+=2)
        if(n%c==0)return 0;
    return 1;
}
int gold(int n)
{
    int p;
    for(p=3;p<=n/2;p+=2)
    if(prime(p)&&prime(n-p))
        return 1;
    return 0;
}
int main()
{
   long long s=clock();
   int start=6,end=20000000,n;
   for(n=start;n<=end;n+=2)
    if(!gold(n))
        puts("Congratulations!");
  long long e=clock();
  printf("%.3f\n",(e-s)/1000.0);
}
